1. Field of the Invention
The present invention relates to a float bath for manufacturing glass, a float glass forming method using the float bath, and a method for installing barriers to the float bath. More particularly, the present invention relates to a float bath for manufacturing glass, which has an improved barrier installation structure for controlling the flow of a molten metal received in the float bath, a float glass forming method using the float bath, and a method for installing barriers to the float bath.
2. Description of the Related Art
Generally, an apparatus for manufacturing a float glass (also known as sheet glass, flat glass, or plate glass) using a float glass process is used to manufacture a float glass having a predetermined size (width, thickness, or the like) by continuously supplying molten glass onto a flowing molten metal such as molten tin or tin alloy stored in a float bath, floating the molten glass on the molten metal to form a molten glass ribbon into a band shape with a constant thickness, and pulling up the glass ribbon toward an annealing lehr near an exit of the float bath.
Here, the molten metal includes, for example, tin or tin alloy, and has a greater specific gravity than the molten glass. The molten metal is received in a float chamber where a reducing atmosphere of hydrogen (H2) and/or nitrogen (N2) gas is introduced. The float bath in the float chamber is configured to contain the molten metal therein. The float bath has a horizontally extending structure and includes a high heat resistant material (for example, bottom blocks) therein. The molten glass forms a molten glass ribbon while moving from an upstream end of the float bath to a downstream end. The molten glass ribbon is lifted up at a location (hereinafter, referred to as a take-off point) set on the downstream end of the float bath to stay away from the molten metal, and delivered to an annealing lehr of the next process. Meanwhile, an inlet and an outlet of the float chamber should have certain temperature gradients. The molten metal contacting the molten glass and the upper site in the float chamber should also have temperature gradients.
However, since tin frequently used as the molten metal rapidly propagates heat and is in liquid state, the temperature gradient in the float bath may be easily broken due to heat convection which equalizes the temperature. Thus, the float bath should have a sufficient length. Similarly, so that the atmosphere of the upper portion of the molten metal has a predetermined equalized temperature difference by convection, the float bath needs a sufficiently long structure. Also, shaping members such as so-called ‘top-roll’ are disposed at a predetermined region of the float bath to enlarge the width of the glass ribbon and thus adjust the thickness of the float glass. Thus, the region where top-rolls are disposed is heated by heating members. Due to this condition, it is also necessary to increase the length of the float bath.
FIG. 1 is a side sectional view showing a conventional float bath, and FIG. 2 is a partially sectioned perspective view showing the conventional float bath of FIG. 1.
Referring to FIGS. 1 and 2, a conventional float bath 1 has a barrier member 3 installed in a width direction of a bottom block 2. The barrier member 3 functions to decrease or limit mixing of molten metals M between a high temperature region and a low temperature region in the float bath 1 to maintain a desired temperature difference (gradient) between two regions. In other words, the barrier member 3 plays a role of keeping the molten metal M in a high temperature forming region at the upstream of the float bath 1. The barrier member 3 is generally made of carbon material, or the like. Also, the barrier member 3 is inserted into a dovetail slot 4 formed in the bottom block 2. An installation groove 6 is provided in the bottom block 2 adjacent to a side block 5 of the float bath 1 so that the barrier member 3 is inserted therein.
However, since the upper portion of the installation groove 6 is opened while the float bath 1 forms a float glass G, the molten metal M is collected in the installation groove 6. In addition, the molten metal M may float in a region above the installation groove 6. As a result, the barrier member 3 of the conventional float bath 1 is not able to block the flow of the molten metal M in at least one end of the float bath 1 in a width direction. Also, the barrier member 3 is limited in controlling the flow of the molten metal M since the molten metal M collected in the installation groove 6 may flow in whirls.
Meanwhile, there are some conventional cases where a barrier is installed over the entire length of a bottom block in a width direction. However, for this purpose, a side block should be installed after barriers are installed over the entire length of the bottom block. In this case, when it is needed to repair or exchange the barrier, the side block should be dismantled from the bottom block, which is very difficult and not economic.